Coupling of SWMM with 2D Hydrodynamic Model for Evaluation of Sponge City Construction

Sponge city is a new urban stormwater management concept proposed by China to solve the urban water environment and security problems. In the planning, construction and management of sponge cities, the stormwater management model (SWMM) is a very effective and widely used simulation tool, but the SWMM cannot accurately simulate the flood inundation. Aiming at this problem, the SWMM is coupled with a two-dimensional hydrodynamic model based on the finite volume method to establish a coupled 1D and 2D hydrodynamic model. A predictor-corrector method with good stability was used in the coupled model to ensure the non-negativity of the water volume of the 2D model cell. Based on the proposed model, a rainwater management model was constructed for a community. The sponge city construction scheme was simulated and analyzed using several typical observed rainstorm events and design rainstorm process with different return periods. The results show that the proposed coupled 1D and 2D hydrodynamic model can effectively simulate the effect of sponge measures and can be applied to the evaluation of sponge city construction. Sponge measures can reduce the flood inundation in the community to a certain extent and indirectly improve the drainage standards.